> For the complete documentation index, see [llms.txt](https://docs.openbrim.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.openbrim.org/developers/paramml-developer-guide/core-objects/finite-elements-objects/femeshsurface/gridlinesx-gridlinesy-gridlinesz.md).

# GridLinesX, GridLinesY, (GridLinesZ)

The GridLinesX and GridLinesY parameters allow the creation of mesh lines along specific lines on their respective axes. In other words, these parameters override the CX and CY parameters. For example, consider the use of the GridLinesY parameter. In bridge design, beam meshes are often created along the X axis. The GridLinesY parameter can be used as reference lines for the beams.

It's important to note that the inputs for the GridLinesY parameter must be ordered according to the Y axis.

The quality of these created meshes is important for the accuracy of all FE analyzes to be made.

**Example:**

```xml
<O N="FEMeshObject4" T="Project" Category="FEM Objects" TransAlignRule="Right">
    <!-- created by ParamML Examples on 08.02.2023 -->
    <O N="RoadwayAlignment" T="Alignment" Station="0" Azimuth="1.57079632679">
        <O T="Circular" Radius="2400" Length="4800" />
        <O T="CrossSection" Station="0" LeftEdgeToHCL="240">
            <O T="CrossSectionSegment" Width="480" Slope="0" />
        </O>
        <O T="ElevationPoint" Station="0" Elevation="0" />
    </O>
    <P N="GridLine1" V="[[0,0],[600,0]]" />
    <P N="GridLine2" V="[[0,240],[600,240]]" />
    <P N="GridLine3" V="[[0,100],[600,160]]" />
    <P N="GridLine4" V="[[0,60],[600,80]]" />
    <P N="GridLine5" V="[[0,120],[1400,60]]" />
    <O N="FEM1" T="FEMeshSurface" Alignment="RoadwayAlignment" CX="15" CY="60" ConstraintPts="[]" MeshDirection="[[0,0,0],[1,0,0],[1,1,0]]" GridLinesY="[GridLine1,GridLine4,GridLine3,GridLine2]" Material="@NULL\|Material" Surface="@NULL\|Surface" CoorSys="@NULL\|CoorSys" Group="@NULL\|FEGroup" IsConstraint="1">
        <O T="Surface">
            <O T="Point" X="0" Y="0" />
            <O T="Point" X="600" Y="0" />
            <O T="Point" X="600" Y="240" />
            <O T="Point" X="0" Y="240" />
        </O>
    </O>
    <O N="FEM2" T="FEMeshSurface" Alignment="RoadwayAlignment" CX="15" CY="60" ConstraintPts="[]" MeshDirection="[[0,0,0],[1,0,0],[1,1,0]]" GridLinesY="[GridLine1,GridLine4,GridLine3,GridLine2]" Material="@NULL\|Material" Surface="@NULL\|Surface" CoorSys="@NULL\|CoorSys" Group="@NULL\|FEGroup" IsConstraint="1">
        <O T="Surface" X="700">
            <O T="Point" X="0" Y="0" />
            <O T="Point" X="600" Y="0" />
            <O T="Point" X="600" Y="240" />
            <O T="Point" X="0" Y="240" />
        </O>
    </O>
    <O N="FEM3" T="FEMeshSurface" Alignment="RoadwayAlignment" CX="15" CY="60" ConstraintPts="[]" MeshDirection="[[0,0,0],[1,0,0],[1,1,0]]" GridLinesY="[GridLine1,GridLine4,GridLine5]" Material="@NULL\|Material" Surface="@NULL\|Surface" CoorSys="@NULL\|CoorSys" Group="@NULL\|FEGroup" IsConstraint="1">
        <O T="Surface" X="1400">
            <O T="Point" X="0" Y="0" />
            <O T="Point" X="600" Y="0" />
            <O T="Point" X="600" Y="240" />
            <O T="Point" X="0" Y="240" />
        </O>
    </O>
    <O N="FEM4" T="FEMeshSurface" CX="15" CY="60" ConstraintPts="[]" MeshDirection="[[0,0,0],[1,0,0],[1,1,0]]" GridLinesY="[GridLine1,GridLine4,GridLine3,GridLine2]" Material="@NULL\|Material" Surface="@NULL\|Surface" CoorSys="@NULL\|CoorSys" Group="@NULL\|FEGroup" IsConstraint="1">
        <O T="Surface" X="-400">
            <O T="Point" X="0" Y="0" />
            <O T="Point" X="300" Y="0" />
            <O T="Point" X="300" Y="240" />
            <O T="Point" X="0" Y="240" />
        </O>
    </O>
</O>
```

![](https://openbrim.atlassian.net/wiki/download/attachments/2163736660/image-20230208-140430.png?api=v2) "FEMeshSurfaces" that do not have alignment object do not have curved edges. To view this example in the library, see (<https://openbrim.org/platform/?application=inc&author=ParamML_Examples_OpenBrIM+Platform&folder=FEM+Objects&obj=objid6zw0pv3bcvbth2fxh9fh7>)

Please proceed to the next page.


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